1. Field of the Invention
The present invention relates to a novel hybridoma, a method for generating the same and an anti-sialic acid-containing glycolipid monoclonal antibody produced by the hybridoma.
2. Description of the Prior Art
Hitherto, anti-sera are prepared by adsorbing the serum from an immunized animal on a variety of antigens. However, anti-sera contain a large number of antibody molecules originated from different B cells (polyclonal) and often cause cross reactions with other antibodies. Therefore, it is difficult to obtain anti-sera with excellent specificity.
Under such circumstances, in 1975, Kohlor developed a hybridoma which produces anti-sheep red blood cell antibody and which is generated by fusing spleen cells derived from an immunized animal and mouse myeloma cells to generate hybridomas. A clone which is a hybridoma originated from a single cell can be isolated from such hybridoma cells (so-called "cloning") because of its high proliferation potency. All the antibodies produced by such a cloned hybridoma are identical, have uniform specificity to an antigen and thus they recognize the same site of a specific antigen. In addition, the hybridomas can be stored in the frozen state, for instance, in liquid nitrogen. Therefore, the stable supply of the individual antibodies can be ensured. Thus, according to cell fusion technique, it becomes possible to obtain a monoclonal antibody highly specific to a specific antigen.
Antibodies are proteins which can recognize a molecule or substance referred to as "antigen" inherent thereto and can be bound to the same. The monoclonal antibody means an antibody having a site which specifically recognizes a specific antigen, in other words it recognizes only one antigenic determinant. Nowadays, various techniques for producing monoclonal antibodies and those for generating hybridomas capable of producing the same are well known in the art. In this respect, reference can be made to a recent publication "Monoclonal Hybridoma Antibodies: Techniques and Applications", edited by John G. Hurrell, 1983.
The glycolipid of mammalian cells belongs to the category of so-called sphingoglycolipid and comprises (a) a lipid structure referred to as ceramide composed of a long chain aminoalcohol called sphingosine to which a fatty acid is amido-bound and (b) various combination of sugars selected from the group consisting of glucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, fucose and sialic acid which are bound to the structure through glycoside linkages. Among these, the glycolipids carrying sialic acid residue are called gangliosides.
Most of these compounds are generally located in the outer cellular membrane and it has been thought from recent investigations that gangliosides play an important role in the functions as a reception and response of recognition and information, receptor functions, differentiation, proliferation, malignant change, or behavior of cells.
Among these gangliosides, GD.sub.3 gangliosides are known as the differentiated antigen of nerve cells and further identified as the cancer-related antigen of human melanoma cells.
Since the monoclonal antibody has high specificity to a specific antigen and thus can detect the same in high sensitivity as disclosed above, if a monoclonal antibody specific to the GD.sub.3 gangliosides is obtained, it would be expected to apply such a monoclonal antibody to diagnosis of cancers (as a cancer marker) and immunological treatment as well as to the elucidation of sugar chain's role in cellular functions.